This invention is directed to an apparatus for tying-up yarn to a yarn package tube and for forming a transfer tail thereon, and particularly to an improved apparatus for tying-up yarn to and for forming a transfer tail on one or more textile or industrial yarn package tubes mounted on the same yarn winder mandrel with each yarn package tube having a groove and cross-cut notch with which the apparatus cooperates to make the tie-up and to form the transfer tail, the yarn package tube, method and an apparatus for practicing the method disclosed in copending U.S. Patent Application Ser. No. 817,276, filed July 20, 1977, the same date as the instant application, in the name of William A. Thomas, Jr.
Other devices and apparatus for forming transfer tails on yarn package supports, particularly on yarn package supports that are rotating at the desired yarn package winding speeds, are well known in the art. Some of these prior art devices or apparatus are represented in the Newman et al patent, U.S. Pat. Nos. 3,971,518; the Spaller patent, 3,999,716; the Pabis patent, 3,276,704; the Rhein, Jr. patent 3,149,795; the Nugent patent, 3,224,692; the Ratti patent, 3,575,355, the Emery patent, 3,428,266; the Porter patent, 3,282,516; and the Bolger patent, 3,275,252.
Other types of yarn package tubes on which transfer tails and yarn packages are wound are also well-known in the art. Some representative patents disclosing such yarn package tubes are Adams et al, U.S. Pat. No. 3,717,291; Sowell, U.S. Pat. No. 3,284,023; Heatherly, 3,103,305; and Pabis 3,276,704. The latter patent, Pabis, also discloses that it is well-known to tie-up yarn at the same time and form transfer tails thereon to two yarn rubes mounted on the same yarn winder mandrel.
The textile winders concerned with this invention usually involve a yarn package support, which may be surface-driven, and where the traversing action for even distribution of the yarn on the yarn package support may be obtained by use of a drive roll having a spiral groove in its surface to traverse the yarn as it is wound on the package, as in the case of the above-mentioned Nugent patent, U.S. Patent No. 3,224,692. The traversing action may also be accomplished by the reciprocating motion of a yarn traverse guide through which the yarn advances to the yarn package support or tube, as in the case of the above-mentioned Newman et al patent, U.S. Pat. No. 3,971,518; Spaller patent 3,999,716; and the Pabis patent, 3,276,704.
The "transfer tail" is an initial wrap or turn or series of wraps or turns in the form of a single layer of a short length of helices at one end of the yarn package support or tube just outside the package portion of the tube. The purpose of the transfer tail is to facilitate the tying of the outer end of yarn from another yarn package to the transfer tail of the yarn package being processed or used in a textile mill so as to preserve the continuity of the operating process without the necessity of shutting equipment down when a yarn package becomes depleted. Hence, the transfer tail yarn quality must be comparable to the rest of the yarn in the package.
The winder for which this invention, the transfer tail apparatus, is particularly adapted is the BARMAG SW4S series Winder, Barmer Machinefabrik A.G., which winds yarn onto packages at speeds in excess of 3000 meters per minute. In making transfer tails on yarn packages at these speeds any excessive slack in the winding system generated following the tie-up or connection of the yarn to the yarn package support or tube can cause a number of problems. "Tie-up", for purposes of this description, means connection of the yarn to the yarn package tube.
Initially, before tie-up of the yarn to the yarn package tube, the yarn is traveling toward the winder at speeds in excess of 3000 meters per minute. The yarn is being taken up by a waste aspirator or air doffer, which also serves to maintain the desired tension on the yarn. Any momentary excessive slack in tension following the moment of tie-up to the yarn package tube can cause a roll wrap around the godet roll that precedes the winder. The roll wrap would thus cause a breakdown of the system. If, for whatever reason, a roll wrap should fortuitously be avoided, despite the presence of undesirable slack, and a successful tie-up should be made to the yarn package tube, slack yarn will be present during winding the first few layers of yarn on the yarn package tube. This can cause separated or spread filaments next to the surface of the tube, and thus cause damage filaments.
Another problem resulting from undesirable slack is that the yarn is not pulled sufficiently tight on the traverse guide, and thus on the pick-up of the yarn by the traverse guide the latter does not pick up all of the filaments at the same time, but instead picks up the remainder on the next reciprocation. This results in the filaments becoming undesirably separated, and can cause a breakdown of the yarn end during subsequent processing.
Still another problem resulting from excessive slack: Since the yarn layers next to the tube surface are not tensioned the same as the outer yarn layers, a potential dye take-up difference problem is created.
The separated filament problem also extends to the transfer tail when the yarn is either of low twist or is a non-TF (non-entangled filament) yarn. The filaments become separated in the transfer tail, with the possibility that the entire strand of yarn may not be tied-up to the next successive package during yarn processing. If the filaments are picked up out of phase, some of the yarn strands will be drawn more than other strands when the yarn being wound is only partially oriented. When the yarn is later processed, such as by undergoing a draw texturing operation, the subsequent resulting different dye take-up in a dyeing process may cause flashes in fabric made from such yarn.
An object of the present invention is to reduce slack in the yarn to a minimum at the time following tie-up or connection of the yarn to the yarn package support or tube.
Some of the transfer tail apparatus and devices in the prior art depend upon yarn tension for causing movement of the transfer tail device. Since yarn tension can vary, this will result in different movement or rotational rates in the transfer tail device which may thus cause the helices to be too closely spaced so as to make it difficult for the operator to find a yarn end and tie-up to the next yarn package. If the transfer tail is too widely spaced, the length of the tail may be too short to enable tie-up to the next yarn package.
For instance, the transfer tail device provided by Barmer Machinenfabrik A.G. on the BARMAG SW4S Winder comprises a light-weight arm that rotates as a result of the yarn releasing a latch and exerting a force on the arm by the tension of the yarn. The spacing between helices or turns in the transfer tail on the yarn package tube depends upon the rate of rotation of the arm which in turn depends upon the tension of the yarn, bearing friction, and inertia of the arm. The latch is connected to the arm, and adjustments made to account for changes in the path of the yarn in order to insure proper release of the latch alter the inertia of the arm. Small changes in the inertia and friction will occur and affect the rotation of the arm since the low yarn tension forces are the only forces for causing rotation of the light-weight arm.
An object of the invention, therefore, is to provide an apparatus which will enable winding of transfer tails on yarn package tubes in a controlled, repeatable manner independent of variations in yarn tension, path of the yarn, and friction changes.
Another object of the present invention is to provide a transfer tail apparatus in which yarn tension has little effect in the operation of the transfer tail apparatus. Yarn tension is relied on only to hold the yarn in its proper place in the transfer tail apparatus as the yarn approaches the winder. Thus, since the transfer tail apparatus is not dependent upon yarn tension for its operation, such yarn tension otherwise tending to be variable, repeatability of the desired transfer tail is made more certain.
In the method and apparatus for practicing the method that are disclosed in the above-mentioned copending William A. Thomas, Jr., patent application, when the yarn is tied-up to the yarn package tube, the waste bunch is disclosed as being wound in and on top of the groove that is formed in the yarn package tube. In one of the disclosed apparatus embodiments, for instance, the one yarn guide illustrated is positioned along one side of the tube (front side as viewed in the drawing) in alignment with the groove. Then when, by means of an air doffer, the yarn tie-up is made to the tube, the yarn running through the yarn guide to the tube is guided thereby to wrap in and on top of the groove in the tube as the tube rotates. In another of the disclosed embodiments, a yarn guide is positioned along the lengths of both the front and back sides (as illustrated) of the tube. The front yarn guide is initially moved to be in alignment with the groove in the tube while at the same time the back yarn guide moves with the front yarn guide to provide the yarn sideways along the tube length toward the groove. After the tie-up, the yarn is guided by the front yarn guide to form a waste bunch in and on top of the groove.
It has since been discovered, however, that the waste bunch that was wound in and on top of the groove would at times be found to be too loosely wound. When this condition occurred, it would occasionally result in damaged yarn in both the waste bunch and the transfer tail. It was thus subsequently discovered in the practice of the invention disclosed in the Thomas, Jr. patent application, that if the waste bunch were wound on the surface of the tube instead of in and on top of the groove, the occasional loose waste bunch was eliminated and the appearance of the transfer tail was greatly improved. Further work established that the yarn guide in front of the tube could remain in a stationary position to one side of the groove during tie-up and the winding of the waste bunch. This greatly simplified the mechanism required for controlling the front yarn guide.
Another problem noticed in the practice of the invention disclosed in the Thomas, Jr. patent application, which turned out to be a potential source of wound-in waste on many of the tubes having yarn wound thereon, was the presence of a long strand of yarn extending from the point of tie-up on the yarn package tube. It was found that the yarn strand was caused by the yarn breaking near the air doffer rather than at the groove in the tube. Further work on this problem showed that if the back or rear guide, as illustrated in the Thomas, Jr. patent application, was modified to move in a nearly horizontal plane at a distance of about one-half inch from the tube and on an approximate level with the axis of the tube, such as the horizontal axis illustrated, the yarn would break between the groove and rear yarn guide or at the rear yarn guide. The length of the yarn strand was thus considerably reduced, and the problems formerly associated with the longer length seem to have been minimized.
Still another object of the invention, therefore, is to provide an apparatus that will result in the winding of tight waste bunches and hence improve the appearance of the subsequently wound transfer tail, and without the problem of unwanted wound-in waste.
The winding of two yarn packages at the same time, when mounted in end-to-end relation on the same mandrel, i.e., a dual winding process, is well-known in the art. The winding is usually carried out in the same direction, as viewed from the end on which winding is initiated in order that unwinding from several packages grouped together will all be in the same direction. Also, in such dual winding processes, it is well-known that the transfer tails for both yarns should be effected substantially simultaneously so as to avoid any possibility of variability in the properties of the yarn in each package. The Parry U.S. Pat. No. 3,488,010 discloses such a dual winding process.
A further object of the present invention is to provide a transfer tail apparatus that may form at the same time a transfer tail on each yarn package tube that may be mounted on the same mandrel of the yarn winder, each yarn package tube being mounted end-to-end on the same winder mandrel.